1. Field of the Invention
The invention relates to a rotary machine with orbiting twin blades, especially for expansion drive units and compressors, which can also be utilized for the field of pumping technology and other work machinery.
2. Description of Related Art
From the U.S. Pat. No. 1,940,384 to Arnold Zöller, there is known a rotary compressor that operates with orbiting twin blades, and more particularly with planar sliders. These planar sliders are forced to move, during rotation, in guiding grooves of an eccentrically supported rotor, and are guided by friction blocks secured therein. As a consequence of the mutual connection of the oppositely located sliders into a single twin blade, there is avoided an increase of the centrifugal forces acting on the blade and, as a result, an increase in the friction work between the blade and the orbit-determining surface of the stator. The filling efficiency of the compressor described there is very high and amounts to 75 to 95%. However, the mechanical efficiency is low as a result of the friction work, ranging between 35 and 65%. This compressor, when operated as a blower, is suited for operation at high rotary speeds, and the filling curve exhibits a linear behavior up to 6000 r.p.m. This compressor was previously used, as the case may be, in the function of a blower, for turbocharging the motors of racing cars.
A significant disadvantage of this type of a compressor is the considerable friction work that is generated in the course of rotation during the rapid forced movement of the blades on the eccentric drum and on the stator wall, which results in a rapid wear of its components.
A multitude of other technical approaches has subsequently concerned itself with the solution of these tribological problems of the aforementioned machine by presenting various alternative constructions that make it possible to accomplish the forced movement of the twin blades situated in the internal space of the rotor, with the aim of reducing the friction work and achieving circular orbiting trajectory of the twin blades.
So, for instance, in the patent documents of JP 56-44489, the twin blades are guided in lateral grooves, as a result of which, however, centrifugal forces increase with increasing rotary speeds and, simultaneously, increase the frictional work. In this solution, moreover, the implementation of only one twin blade is optimized, similarly to another known solution according to the Austrian patent document AT 920009.
In further documents U.S. Pat. No. 3,001,482, DE-PS 433,963 and U.S. Pat. No. 3,294,454, the blades are again guided in lateral grooves; that brings about high frictional resistance during rotation. In the U.S. Pat. No. 2,070,662, the movement of the freely inserted blades is forced by an eccentrically supported rotor entraining member.
The solution in accordance with the patent document FR-A 1091637 is characterized by blades that are pressed against the orbit-determining surface, which again results at higher rotary speeds in an increased friction work.